Add documentation for bot_loop_start

docs/strategy-advanced.md

@@ -89,3 +89,30 @@ class Awesomestrategy(IStrategy):
             return True
         return False
 ```
+
+## Bot loop start callback
+
+A simple callback which is called at the start of every bot iteration.
+This can be used to perform calculations which are pair independent.
+
+
+``` python
+import requests
+
+class Awesomestrategy(IStrategy):
+
+    # ... populate_* methods
+
+    def bot_loop_start(self, **kwargs) -> None:
+        """
+        Called at the start of the bot iteration (one loop).
+        Might be used to perform pair-independent tasks
+        (e.g. gather some remote ressource for comparison)
+        :param **kwargs: Ensure to keep this here so updates to this won't break your strategy.
+        """
+        if self.config['runmode'].value in ('live', 'dry_run'):
+            # Assign this to the class by using self.*
+            # can then be used by populate_* methods
+            self.remote_data = requests.get('https://some_remote_source.example.com')
+
+```

freqtrade/freqtradebot.py

@@ -151,6 +151,8 @@ class FreqtradeBot:
         self.dataprovider.refresh(self.pairlists.create_pair_list(self.active_pair_whitelist),
                                   self.strategy.informative_pairs())
 
+        strategy_safe_wrapper(self.strategy.bot_loop_start)()
+
         self.strategy.analyze(self.active_pair_whitelist)
 
         with self._sell_lock:

freqtrade/strategy/interface.py

@@ -194,7 +194,7 @@ class IStrategy(ABC):
         """
         Called at the start of the bot iteration (one loop).
         Might be used to perform pair-independent tasks
-        (e.g. like lock pairs with negative profit in the last hour)
+        (e.g. gather some remote ressource for comparison)
         :param **kwargs: Ensure to keep this here so updates to this won't break your strategy.
         """
         pass

freqtrade/templates/subtemplates/strategy_methods_advanced.j2

@@ -1,4 +1,13 @@
 
+def bot_loop_start(self, **kwargs) -> None:
+    """
+    Called at the start of the bot iteration (one loop).
+    Might be used to perform pair-independent tasks
+    (e.g. gather some remote ressource for comparison)
+    :param **kwargs: Ensure to keep this here so updates to this won't break your strategy.
+    """
+    pass
+
 def check_buy_timeout(self, pair: str, trade: 'Trade', order: dict, **kwargs) -> bool:
     """
     Check buy timeout function callback.

tests/strategy/test_interface.py

@@ -57,6 +57,9 @@ def test_returns_latest_signal(mocker, default_conf, ohlcv_history):
 
 def test_trade_no_dataprovider(default_conf, mocker, caplog):
     strategy = DefaultStrategy({})
+    # Delete DP for sure (suffers from test leakage, as we update this in the base class)
+    if strategy.dp:
+        del strategy.dp
     with pytest.raises(OperationalException, match="DataProvider not found."):
         strategy.get_signal('ETH/BTC', '5m')
 
@@ -418,6 +421,14 @@ def test_is_pair_locked(default_conf):
     assert not strategy.is_pair_locked(pair)
 
 
+def test_is_informative_pairs_callback(default_conf):
+    default_conf.update({'strategy': 'TestStrategyLegacy'})
+    strategy = StrategyResolver.load_strategy(default_conf)
+    # Should return empty
+    # Uses fallback to base implementation
+    assert [] == strategy.informative_pairs()
+
+
 @pytest.mark.parametrize('error', [
     ValueError, KeyError, Exception,
 ])